I'll buy some shift registers in the near future and would like to ask which oneI should buy... I'll certainly go for the 74HC595 but which version. There is onewith DIL-16 and one with SO-16 enclosure. I unfortunatly don't know what thatmeans... can anyone help me?

(oh by the way, is it normal that white LEDs are alot more expensive than allthe other colors?)

I'll buy some shift registers in the near future and would like to ask which oneI should buy... I'll certainly go for the 74HC595 but which version. There is onewith DIL-16 and one with SO-16 enclosure. I unfortunatly don't know what thatmeans... can anyone help me?

You want DIL-16, because the SO-16 are very,very small therefore hard to solder especially if you are a beginner in electronics.

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(oh by the way, is it normal that white LEDs are alot more expensive than allthe other colors?)

To clarify, the DIL package is the style of the ATMEGA chip on your Arduino and the SO package is the style of the USB driver chip.

For your LEDs look at www.ledshoppe.com. They have white LEDs, a package of 100 for $10 including shipping, and if you sign up for the newsletter, they'll even through in a keychain laser pointer/flashlight.

I've bought from them and they seem to have good customer service as well as good products.

ok, and another question... I don't want to spam the board, so I'll ask here:Is there an easy way to calculate the approximate time arduino runs on battery?

I'll use around 50 leds. I remember there was some kind of a formula. I shouldbe able to calculate this if I know what kind of battery I'll use and how much theLEDs need, right?

It depends on the batteries as well as what's being powered.

For AA recharable NiMH batteries, you have around 2 amp-hours. An LED takes about 20 mA and the Arduino takes about 20mA. So if you had all 50 LEDs on at once, you'd be using about 1000mAh, and the batteries would last about 2 hours.

thank you! I might have to rethink my concept then. It's supposed to be some kindof a wrist watch .

In the pre-LCD days, there were LED wrist watches. The way they solved this is that they were off all the time. There was a button to make the display come on for a few seconds. There were also more advanced versions that had motion switches so you could swing your arm a certain way to get the display to come on.

But for parts, have a look on ebay, particularly if you want to buy in quantity and don't mind waiting a week or so for items to be shipped from china.

You could also try dealextreme, they have a eclectic range of LEDs, such as:

20 packs of red, green or orange for $2.35 each including shippinghttp://www.dealextreme.com/details.dx/sku.11099http://www.dealextreme.com/details.dx/sku.11100http://www.dealextreme.com/details.dx/sku.11101

or this 60 lumen! white emitter for $2.75 including shipping.http://www.dealextreme.com/details.dx/sku.13286

thank you for these suggestions. I have two shops in switzerland but theyare not very cheap and lack certain items.

what kind of resistors do I need? I thought the ones I got with myarduino kit are coal resistors. but the shop I have here lists them startingat 1W. But I would need one at around 0.33W.

now they have also metal oxyde resistors, but they seem to be much moreexpensive. is that possible, or could it be an errpr in the shop system (theylist the price per 1 resistor, where the coal ones are listed as per 100 items).

for the german speaking readers, this is the shop I'm talkin about, maybe youcan help: